A rundown on how some nations across the world are reacting to the new war.
Authorities on Saturday and Sunday stepped up security measures around Jewish sites in France, Germany and the United Kingdom, due to the conflict between Israel and Hamas.
Meanwhile, demonstrations in support of the Palestinians took place in several countries in the Middle East.
Security was strengthened on Saturday around places of worship and Jewish educational establishments in France, particularly in Paris and its suburbs.
The move came despite an announcement from Interior Minister Gérald Darmanin, who insisted there was currently "no threat".
The security of Israeli sites of interest and places of worship had already been reinforced in mid-September with the start of the Jewish new year marked by the celebrations of several holidays in September and October.
Germany has strengthened security around buildings of the Jewish community and the Israeli representation after Hamas attacks against Israel, German Interior Minister Nancy Faeser told the daily Bild newspaper on Saturday.
The German authorities are also keeping an eye on "potential Hamas supporters in the Islamist sphere very closely", the minister stressed.
Berlin police also cited photos on X - formerly Twitter - which allegedly "show people celebrating the attacks on Israel by distributing sweet pastries on Sonnenallee", an avenue in the Neukölln district known for its diversity and its large Muslim population.
London police increased patrols in parts of the British capital on Sunday after "incidents" linked to the war between Israel and Hamas, and the Interior Minister called for "zero tolerance" against the "glorification of terrorism".
“Police have increased patrols in parts of London to ensure a visible presence and reassure our communities,” the Metropolitan Police announced.
Secretary of State for Immigration Robert Jenrick shared a video on the social network X showing people waving Palestinian flags in the street and sounding car horns.
Demonstrations in support of Palestinians in the Middle East
In Turkey, Iraq, Iran, Syria, Lebanon, and Yemen, demonstrations in support of the Palestinians took place on Saturday and Sunday.
In Iran, a country whose president said he supports "the legitimate defence of the Palestinian nation" and holds Israel "responsible", several hundred people demonstrated on Sunday in several major cities in Iran, including its capital Tehran, waving the Palestinian flag.
In Tehran, large posters read: “the great liberation operation has begun”, while Israeli flags were burned.
In the streets, motorists with Palestinian flags honked their horns to express their joy and fireworks were set off in several localities - according to the official IRNA agency.
In Lebanon, Hezbollah organised a rally on Sunday in its stronghold in the southern suburbs of Beirut to support the Palestinian offensive.
A senior member of the Lebanese movement, Hachem Safieddine, paid tribute to "the heroes of Gaza" and affirmed that "the time for revenge has come". He was cheered on by his supporters who chanted "Death to Israel".
In Damascus, young people are said to have distributed pastries to cars in a central square in the Syrian capital as a sign of celebration.
Thousands of Turks have taken part in a march in Istanbul to support the Palestinians.
“The Palestinian people are only defending their homeland, it has nothing to do with terrorism,” Sahin Ocal, 54, an activist from one of the associations organising the march, told AFP.
In Sanaa, demonstrators gathered in support of the Palestinians and burned Israeli and American flags. Houthi militiamen, supported by Iran and who control Sanaa, chanted “Death to America, death to Israel”.
A demonstration in support of the Palestinians is expected late on Sunday in the holy Shiite city of Karbala.
On Saturday, around 100 protesters gathered in the capital Baghdad in a downtown square to celebrate the Hamas offensive, waving Palestinian flags. Protesters trampled and set fire to Israeli flags and chanted "no to the United States, no to Israel."